Drilling is one of the types of material by cutting. This method uses a special cutting tool - a drill. Can be used to make a hole different diameter, as well as depth. In addition, it is possible to create multifaceted holes with different cross sections.

Purpose of the operation

Drilling is a necessary operation if you want to get a hole in metal product. Most often, there are several reasons for drilling:

• need to create a hole for threading, or boring;
• it is necessary to place electrical cables, fasteners in the holes, pass anchor bolts through them, etc.;
• blanks department;
• weaken collapsing structures;
• depending on the diameter of the hole, it can even be used for laying explosives, for example, in the extraction of natural stone.

This list can be continued for a long time, but we can already conclude that the drilling operation is one of the simplest and at the same time quite necessary and common things.

Expendable materials

Naturally, to carry out the drilling process, it is necessary to have drills. Depending on this consumable, the diameter of the hole will change, as well as the number of its faces. They may be round section, and can be multifaceted - triangular, square, five-sided, six-sided, etc.

In addition, drilling is an operation in which the drill will heat up to high temperatures. For this reason, it is necessary to accurately select the quality of this element, based on the requirements of the material with which you will have to work.

• A fairly common material for the production of drilling fixtures is carbon steel. Elements of this group are marked as follows: U8, U9, U10, etc. The main purpose of such consumables is drilling holes in wood, plastic, and soft metals.
• Next come drills made of low alloy steel. They are intended for drilling the same materials as carbon ones, but their difference lies in the fact that this brand of elements has an increased heat resistance value of up to 250 degrees Celsius, and also an increased drilling speed.

Improved drills

There are several types of drills that are designed for higher quality materials:

• The first type of drill is made from high speed steel. The heat resistance of these consumables is much higher - 650 degrees Celsius, and they are designed for drilling any construction materials in an unheated state.
• The next group is carbide drills. They are used to make holes in any structural non-hardened steels, as well as in non-ferrous metal. A feature is that drilling at high speeds is used. For the same reason, the heat resistance is increased to 950 degrees Celsius.
• One of the most persistent elements These are Borazon drills. Are applied to works with cast iron, steels, glass, ceramics, non-ferrous metals.
• The last group is diamond drills. Are applied to drilling of the hardest materials, glass, ceramics.

Types of drilling machines

The following types of drilling machines can be used to carry out the drilling operation:

• Vertical and horizontal drilling devices. Drilling holes for such machines is the main operation.
• Used vertical and horizontal type. Drilling is considered ancillary operations for these devices.
• Vertical, horizontal and universal machines milling type. For these units, drilling is also a secondary operation.
• Lathes and lathes. On the first type of devices, the drill is a fixed part, and the workpiece itself rotates. For the second type of device, drilling is not the main operation, and the drill is a fixed element, as in the first case.

These are all types of drilling machines on which all the required operations can be carried out.

Hand tools and auxiliary operations

In order to facilitate the drilling process, several auxiliary operations are used. These include the following:

• Cooling. When drilling, a variety of cutting fluids are used. These include, for example, water, emulsions, oleic acid. Also can be used gaseous substances, for example carbon dioxide.
• Ultrasound. The ultrasonic vibrations produced by the drill are used to increase the productivity of the process as well as to enhance chip breaking.
• Heating. In order to improve drilling in metal having high density, it is preheated.
• Hit. For some surfaces, such as concrete, it is necessary to use rotary and impact motions to increase productivity.

This procedure can be carried out not only on machines in automatic mode, but also on manual equipment. Manual drilling involves the use of tools such as:

• Mechanical drill. For drilling, the mechanical force of a person is used.
• Electric drill. It can carry out conventional and shock-rotary drilling. Works from an electric network.

Types of procedure and cooling

There are several main types of drilling - this is the equipment of cylindrical holes, polyhedral or oval, as well as reaming existing cylindrical holes to increase their diameter.

The main problem that arises in the process of drilling metal is the strong heating of the consumable element, that is, the drill, as well as the place of work. The temperature of the material can reach 100 degrees Celsius or more. If it reaches certain values, then combustion or melting may occur. It is important to note here that many steels that are used to make drills lose their hardness when heated, which will only increase friction, so the element will, unfortunately, wear out faster.

In order to combat this shortcoming, various coolants are used. Most often when vertical drilling on the machine it is possible to organize the supply of coolant directly to the place of work. If it is carried out using hand tools, then after a certain period of time it is necessary to interrupt the process and dip the drill into the liquid.

The essence of drilling

Hole drilling technology is the process of forming grooves by removing chips in solid material with a cutting tool. This element performs rotational and translational or rotational-translational movements at the same time, which forms a hole.

The use of this type of material processing is used in order to:

• obtain irresponsible holes with a low degree of accuracy and roughness class used for fixing bolts, rivets, etc.;
• get holes for tapping, reaming, etc.

Processing Options

Using the procedure of deep drilling or reaming, holes can be obtained that will be characterized by the 10th or 11th degree of surface roughness. If it is necessary to obtain a better hole, then after the completion of the processing process, it is necessary to additionally countersink and expand it.

In order to increase the accuracy of work, in some cases, you can resort to careful adjustment of the position of the machine, properly sharpened consumables. Also, a method is used in which work is carried out through special device, which improves accuracy. This device called a conductor. There is also a division of drills into several classes. There are spiral with straight grooves, feather, used for deep or core drilling and center drills.

Drill Design Description

Most often, the usual is used for work. Special ones are used much less frequently.

The spiral element is a two-tooth cutting part, which includes only two main parts - a shank and a working part.

If we talk about the working part, then it can be divided into cylindrical and calibrating. On the first part of the drill, there are two helical grooves opposite each other. The main purpose of this part is the chips that stand out during operation. It is important to note here that the grooves have correct profile that provides the right education cutting edges drill. In addition, the necessary space is created, which is necessary for the removal of chips from the hole.

Drilling technology

Here it is important to know a few certain rules. It is very important that the shape of the flutes, as well as the angle of inclination between the direction of the axis of the drill and the tangent to the belt, be such as to ensure easy chip evacuation without weakening the section of the teeth. However, it is worth noting here that this technology, and especially the numerical values, will change markedly depending on the diameter of the drill. The thing is that an increase in the angle of inclination leads to a weakening of the action of the drill. This disadvantage is more pronounced, the smaller the diameter of the element. For this reason, you have to adjust the angle for the drill. The smaller the drill, the less angle, and vice versa. The total angle of the grooves is from 18 to 45 degrees. When it comes to drilling steel, it is necessary to use drills with an inclination angle of 18 to 30 degrees. If holes are made in fragile materials, such as brass or bronze, then the angle is reduced to 22-25 degrees.

Principles of work

It is important to start with the fact that, depending on the material of the tool, and will change. For example:

• If drilling is carried out using tool steel elements, then minimum speed is 25 m/min, and the maximum is 35 m/min.
• If machining is carried out with drills belonging to the category of high-speed cutting, then the minimum speed is 12 m/min, and the maximum speed is 18 m/min.
• If carbide drills are used, the values ​​are 50 m/min and 70 m/min.

It is important to note here that the drilling technology involves the choice of the speed of the procedure depending on the diameter of the element itself and low feed (with an increase in the diameter, the speed also increases).

A characteristic feature of the work is the use of a standard angle at the top for the drill, which is 118 degrees. If it is necessary to work with raw materials, which are characterized by a high hardness of the alloy, then the angle must be increased to 135 degrees.

Safety of drills

One of the important tasks in carrying out this type of machining was the need to preserve the cutting properties of the consumable. The safety of these parameters directly depends on which method of operation was chosen and whether it was suitable for this material. For example, in order to eliminate the breakage of the drill on the pass, it is necessary to greatly reduce the feed at the moment the drill is withdrawn from the hole.

Particular attention should be paid to drilling technology in situations where the depth of the hole exceeds the length of the helical groove of the consumable. At the time of insertion of the drill, chips will still form, but during the exit it will no longer be. Because of this, drills break very often. If there is no way out of the situation, then you need to periodically withdraw the drill and manually clean it of unnecessary elements, that is, chips.

Drill bits

In order to make a hole in a certain coating, it is necessary to use crowns. However, they also need to be chosen correctly, based on certain parameters. Currently, three main types of material are used to create crowns - this is diamond, win and tungsten carbide. A feature of the diamond crown is that it performs impactless drilling. In this case, a more correct hole geometry is obtained.

The main advantages of diamond nozzles were the following: the ability to cut reinforced concrete materials, low level noise and dust, no violation of the structure of the structure, since the technology does not use impact force.

drilling

Drilling, countersinking and reaming

Drilling is the process of removing metal to make holes. The drilling process includes two movements: tool rotation V(fig. 48) or parts around the axis and feed S along the axis. The cutting edges of the drill cut off thin layers of metal from a fixed part, forming chips that, sliding along the spiral grooves of the drill, exit the hole being machined. The drill is multi-blade cutting tool. Not only the two main blades are involved in cutting, but also the jumper blade, as well as two auxiliary drills located on the guide ribbons, which greatly complicates the process of chip formation. When considering the scheme of chip formation during drilling, it is clearly seen that the working conditions of the cutting edge of the drill at different points of the blade are different. So, the rake angle of the cutting edge at(fig. 49),

Rice. 48. Scheme of cutting when drilling. Forces acting on the drill

Rice. 49. Chip formation during drilling

located closer to the periphery of the drill (section A-A), is positive. The cutting edge works in relatively light conditions.

The front angle of inclination of the cutting edge, located further from the periphery, closer to the center of the drill (section B-B), is negative. The cutting edge works in more difficult conditions than those located closer to the periphery.

Cutting with a transverse cutting edge ( section C-C) is a cutting process close to extrusion. When drilling, compared to turning, the conditions for chip removal and coolant supply are much worse; there is a significant friction of the chips on the surface of the drill grooves, the friction of the chips and the drill on the machined surface; along the cutting edge there is a sharp difference in cutting speeds - from zero to maximum, as a result of which, at various points of the cutting edge, the cut layer is deformed and cut off with different speed; along the cutting edge of the drill, the deformation is different - as it approaches the periphery, the deformation decreases. These features of cutting during drilling create more difficult conditions for chip formation compared to turning, an increase in heat generation and increased heating of the drill. If we consider the process of chip formation in individual micro sections of the cutting edge, then elastic and plastic deformations, heat generation, build-up formation, hardening, and tool wear arise here for the same reasons as in turning. Cutting temperature in drilling is more influenced by cutting speed than by feed.

Fig.50. twist drill

Drill elements. The most common and universal purpose is a twist drill (Fig. 50). The drill consists of a working part, a conical or cylindrical shank, which serves to fix the drill, and a paw, which is a stop when the drill is removed. The working part of the drill is a cylindrical rod with two spiral or helical grooves, along which chips are removed. The cutting part is sharpened along two conical surfaces, has a front and back surfaces (Fig. 50) and two cutting edges connected by a jumper at an angle of 55 °. On the cylindrical part, two narrow ribbons pass along the helical line, centering and guiding the drill in the hole. Ribbons significantly reduce the friction of the drill on the walls of the hole being machined. To reduce friction of the working part of the drill towards the shank, a reverse cone is made. The drill diameter decreases for every 100 mm of length by 0.03-0.1 mm.

The cutting part of the drill is made from tool steels in hard alloys. Like the cutter, the drill has front and back angles (Fig. 51). Front angle at(section B-B) at each point of the cutting edge is a variable value. Highest value injection at has on the periphery of the drill, the smallest at the top of the drill. Due to the fact that the drill not only rotates during operation, but also moves. along the axis, the actual value of the relief angle a different from the angle, by-. radiated during sharpening. The smaller the diameter of the circle on which the considered point of the cutting edge is located, and the greater the feed, the smaller the effective relief angle.

Valid same rake angle during the cutting process, respectively, there will be more than the angle measured after sharpening. To ensure a sufficient clearance angle in work

Purpose of drilling

Drilling is a necessary operation to obtain holes in various materials when processing them, the purpose of which is:

• Making holes for threading, countersinking, reaming or boring.
• Making holes (technological) for placement in them electrical cables, anchor bolts, fasteners and etc.
• Separation (cutting off) of workpieces from sheets of material.
• Weakening of destructible structures.
• The laying of an explosive charge in the extraction of natural stone.

Drilling machines and tools

Drill body with indexable carbide inserts

Drilling of cylindrical holes, as well as drilling of multifaceted (triangular, square, five- and hexagonal, oval) holes is performed using special cutting tools - drills. Drills, depending on the properties of the material being processed, are made of the required standard sizes from the following materials:

• Carbon steels (U8, U9, U10, U12, etc.): Drilling and reaming of wood, plastics, soft metals.
• Low-alloy steels (Х, В1,9ХС,9ХВГ, etc.): Drilling and reaming of wood, plastics, soft metals. Increased heat resistance (up to 250 °C) and cutting speed compared to carbon steels.
• High-speed steels (R9, R18, R6M5, R9K5, etc.): Drilling of all structural materials in a non-hardened state. Heat resistance up to 650 °C.
• Drills equipped with hard alloy, (VK3, VK8, T5K10, T15K6, etc.): Drilling at high speeds of non-hardened steels and non-ferrous metals. Heat resistance up to 950 °C. Can be solid, with soldered plates, or with replaceable plates (attached with screws)
• Drills equipped with borazon: Drilling of hardened steels and white cast iron, glass, ceramics, non-ferrous metals.
• Drills equipped with diamond : Drilling hard materials, glass, ceramics, stones.

Drilling operations are performed on the following machines:

• Vertical drilling machines: Drilling is the main operation.
• Horizontal drilling machines: Drilling is the main operation.
• Vertical boring machines: Drilling is an auxiliary operation.
• Horizontal boring machines: Drilling is an auxiliary operation.
• Vertical milling machines: Drilling is an auxiliary operation.
• Horizontal milling machines: Drilling is an auxiliary operation.
• Universal milling machines: Drilling is an auxiliary operation.
• Lathes: The drill is stationary and the workpiece rotates.
• Resurfacing lathes: Drilling is an auxiliary operation. The drill is stationary.
• Turret lathes: Drilling is an auxiliary operation. The drill can be stationary (static block) or rotated (driven block)

And on manual equipment:

• Mechanical drills: Drilling using human muscle power.
• Electric drills: Drilling on installation with portable power tools (including impact drilling).

To facilitate the cutting process of materials, the following measures are used:

• Cooling: Coolants and gases (water, emulsions, oleic acid, carbon dioxide, graphite, etc.)
• Ultrasonic : Ultrasonic vibration of the drill increases productivity and chip breaking.
• Heating: Heating weakens the hardness of difficult-to-machine materials.
• Blow: When shock-rotary drilling (drilling) of stone, concrete.

Types of drilling

• Drilling cylindrical holes.
• Drilling multifaceted and oval holes.
• Reaming of cylindrical holes (diameter increase).
• Centering: Drilling out a small amount of material to position another drill (for example, when deep drilling) or to fix the part with a rear center.
• Deep drilling: Drilling to a depth of 5 or more hole diameters. Often requires special technical solutions.

Cooling while drilling

A big problem when drilling is the strong heating of the drill and the material being processed due to friction. At the drilling site, the temperature can reach several hundred degrees Celsius.

If heated too much, the material may start to burn or melt. Many steels lose their hardness when heated strongly, as a result, the cutting edges of steel drills wear out faster, due to which friction only increases, which ultimately leads to a quick failure of the drills and a sharp decrease in drilling efficiency. Similarly, when using a carbide drill or an indexable drill, the carbide loses its hardness when overheated and plastic deformation of the cutting edge begins, which is an undesirable type of wear.

Cooling with the help of cooling emulsions or cutting fluids (coolant) is used to combat heating. When drilling on the machine, it is often possible to organize the supply of fluid directly to the drilling site. Coolant can also be supplied through channels in the drill itself if the machine allows it. Such channels are made in many solid drills and in all body drills. Internal coolant supply required when drilling deep holes(depth 10 or more diameters). In this case, it is not so much cooling that is important, but chip removal. Coolant pressure flushes chips out of the cutting area, avoiding chip jamming or re-cutting. If in this case it is impossible to organize the supply of coolant, then it is necessary to carry out drilling with periodic withdrawals of the drill to remove chips. This method is extremely inefficient.

When drilling hand tool drilling is interrupted from time to time and the drill is dipped into a container with liquid.

see also

Links

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See what "Drilling" is in other dictionaries:

drilling- - mechanical processing of a refractory product drilling tool to obtain holes of a given size. [GOST R 52918 2008] Drilling is a selection round holes and sockets for spikes, screws and bolts or knots followed by ... ... Encyclopedia of terms, definitions and explanations of building materials

Cutting wood with a rotating cutting tool fed along the axis of rotation to produce holes. Drilling tools are drills driven by a drill, a brace, a wrench or a drill. See also: Wood cutting Drills… Financial vocabulary

Drilling, turning, drilling, drilling, drilling, turning, drilling, drilling Dictionary of Russian synonyms. drilling n., number of synonyms: 12 anatresis (2) ... Synonym dictionary

drilling- Axial drilling [GOST 25761 83] drilling The process of making holes in a material using a drill [ Terminological dictionary on construction in 12 languages ​​(VNIIIS Gosstroy USSR)] Topics machining EN boringdrilling DE Bohrén … Technical Translator's Handbook

The formation of a through or blind cylindrical hole in the material with a drill. It is carried out manually with a drill and other tools or on drilling, turning, revolving and other machines ... Large encyclopedic Dictionary

DRILLING, drilling, pl. no, cf. (specialist.). Action under ch. drill in 1 digit Dictionary Ushakov. D.N. Ushakov. 1935 1940 ... Explanatory Dictionary of Ushakov

DRILL, lu, only; linen (yon, ena); nesov. Explanatory dictionary of Ozhegov. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory dictionary of Ozhegov

DRILLING- the process of formation of a through or blind cylindrical hole in a solid material by mechanical cutting and removal of material in the form of chips (see), usually performing rotational and translational movements (along the axis of the hole) ... ... Great Polytechnic Encyclopedia

Drills (or perks) and drilling machines. Making cylindrical holes by rotating the tool, the so-called. drilling, was practiced already in prehistoric times. In the remains of pile buildings, fish bones with ears were found, ... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

I; cf. to Drill. Speed ​​with. C. holes. ◁ Drilling, oh, oh. From work. C. shop. C. machine. With th installation. * * * drilling the formation of a through or blind cylindrical hole in metallic and non-metallic materials. ... ... encyclopedic Dictionary

Books

• Drilling of wood and wood materials, Glebov Ivan Tikhonovich, The book discusses the kinematics and dynamics of the drilling process, shows the dependence of torque on cutting forces and drilling mode parameters. Surfaces and cutting planes are considered ... Category:

Llaboratory work number 3

Drilling machines and types of work performed

The purpose of the work: to study the device and purpose of the drilling machine, the work performed on it, the center tool used.

In the process of performing the work, it is necessary to study the main components of the drilling machine, their kinematics and functional purpose. Determine the main and auxiliary movements and elements of the cutting mode when performing drilling work.

There are different types of drilling machines: vertical drilling, radial drilling, horizontal boring, aggregate, jig boring.

Drilling machines are designed for drilling, countersinking, reaming, threading and other types of hole processing (countersinking, countersinking, etc.)

A typical vertical drilling machine is the machine model 2H118, designed for processing small and medium-sized parts (Figure 1).

On the foundation plate 1, which is the base of the machine, a monolithic column 9 (machine bed) is fixed, having vertical guides in the form of a dovetail. Table 2 moves along the vertical guides of the column, which serves to fasten the workpieces to be processed, and the drilling head 7, in which all the main components of the machine are mounted: speed box 5, feed box 4 and spindle 3. The machine drive includes an electric motor 6 with a power of 1.5 kW. The feed mechanism is controlled by handle 8.

When performing drilling operations on the machine, the main working movement is the rotation of the tool (drill, countersink, reamer, tap, countersink, etc.), and the feed movement is the movement of the tool in the axial direction (in this case, vertical). The main movement is transmitted to the spindle from the electric motor through a gearbox that provides various spindle speeds. The feed mechanism provides various speeds of vertical movement of the spindle with the tool.

Drilling is making a hole in a solid workpiece. The operation is performed with a drill. Drill designs various applications are shown in Figure 2. The design of the twist drill is shown in Figure 3.

With the help of twist drills, holes with a diameter of up to 80 mm are made. Cylindrical shank is usually found in drill diameter 12mm, it is used for fastening in a drill chuck and ends with a leash that protects the drill from turning. The tapered shank (Morse taper) ends with a foot that serves to transmit torque and to remove the tool from the spindle. Between the shank and the working part, drills with a diameter of more than 5 mm have a neck on which the tool marking is applied. The neck serves to exit the grinding wheel during the manufacture and sharpening of the drill, as well as for marking. The neck may be absent if the shank diameter is larger than the diameter of the calibrating part of the drill.

The working part of the drill has two spiral grooves and ends with a cone - the cutting part. At the intersection of the helical grooves with the cone (front and main back surfaces), two main cutting edges are formed that perform the main cutting work (Fig. 4).

The main cutting edges, when mated with each other, form a transverse blade - a jumper (auxiliary cutting edge). The jumper is located relative to the main cutting edges at an angle
and cuts metal with difficulty. In order to prevent the drill from shifting, the workpiece is first centered with a short twist drill of large diameter or a special center drill with a 90 degree angle at the top. Holes with a diameter of more than 30 mm are drilled in two stages. First, a hole is drilled with a diameter slightly exceeding the length of the drill jumper, and then the hole is reamed to the required diameter.

To reduce the friction of the guide part of the drill against the walls of the hole being drilled, its diameter has a variable section, decreasing towards the shank. For the same purposes outside surface the guide part of the drill is milled and two protruding ribbons are left, located along the helical grooves. The edges of the ribbons clean the cylindrical surface of the drilled hole, so they are considered auxiliary cutting edges. Thus, the twist drill has five cutting edges - two main and three auxiliary.

The two main cutting edges form a corner at the top (entry angle). For drilling soft materials
, for hard and brittle
. Standard drills are designed for drilling structural steels and have an angle
.

When drilling a hole, the depth of which is greater than its diameter, the drill is periodically withdrawn from the hole being machined and the flutes of the drill and the hole in the workpiece are cleaned from accumulated chips. To reduce the friction of the tool against the walls of the hole, drilling is carried out with the supply of a cutting fluid (coolant), especially when machining steel and aluminum blanks. Cast iron, brass and bronze workpieces can be drilled without cooling. The use of coolant allows you to increase the cutting speed by 1.4-1.5 times.

To increase the efficiency of work with twist drills, along with pre-drilling of holes, methods such as transverse edge sharpening, changing the angle at the top, ribbon sharpening, and double sharpening are used.

The forms of sharpening the cutting part of the drill are shown in Figure 5: a) - normal, b) - normal with a jumper point, c) - normal with a jumper and ribbon point, d) - double with a jumper point, e) - double with a jumper and ribbon point .

Elements of the cutting mode when drilling:

- cutting speed (m/min), circumferential speed of the point on the cutting edge furthest from the drill axis:

;

- outer diameter of the drill, mm;

- drill rotation frequency, rpm.

Drill feed (mm / rev), this is the amount of axial movement of the drill in one revolution. Depth of cut (mm):

when drilling
,

when reaming
,

where - pre-drilled hole diameter (mm).

Work order:

1. Study the guidelines for laboratory work.

2. Get an individual task from the teacher, including the model of the machine, as well as the movements of the machine and the elements of the cutting mode, the parameters of which must be calculated.

3. Study the functional purpose of the main components of the drilling machine, make a sketch with the general layout of the machine, where to designate the main components.

4. Study the kinematic diagram of the drilling machine. Compose calculation expressions and determine the speeds of the movements of the machine set by the teacher. Draw kinematic diagrams.

5. Study the tool used on the machine, its geometry.

6. Compile a report for laboratory work which include all the previously listed items.

Ensuring the quality of processing when drilling

Drilling holes with parallel axes

Depending on the nature of the production, the simultaneous processing of these holes is carried out either on multi-spindle machines with adjustable spindle positions, or on multi-spindle heads installed on single-spindle machines or power heads of an aggregate machine. When drilling using multi-spindle heads, the drill is guided along the drill bushings installed in the jig or in the pressure jig plate. In the latter case, the workpiece is mounted on the machine table in a fixture that is oriented with a multi-spindle head using guide columns.

Drilling side holes

When processing four or more holes on multi-spindle machines, the use of manual feed turns out to be irrational, due to an increase in axial forces and uneven feeds. In this regard, special multi-position machines with a pneumohydraulic drive have become widespread. On such a machine, it is possible to process parts that have radially arranged holes in planes of different heights. Re-adjustment of the machine consists in changing the jig, clamping collets, drills and installing drilling heads at the appropriate angle.

Quick changeover, small losses of time, combination of machine time during drilling make it possible to use this machine in conditions of serial and even small-scale production.

Drilling holes located in mutually perpendicular areas.

At the same time, such holes can be machined on modular machines composed of normalized units.

Possible drill hole defects

1. The diameter of the drilled hole is slightly larger than the diameter of the drill. Reasons: the cutting edges of the drill are of unequal length. The defect is uncorrectable.

2. The axis of the hole does not match the axis of the part. Cause: the drill is pulled to the side at the beginning of drilling. The defect is uncorrectable.

3. The hole diameter is larger than the drill diameter and the conical bottom is stepped. Reason: unequal length and inclination of the cutting edges and the axis of the drill. The defect is uncorrectable.

4. Hole dimensions are larger at the edges than in the middle. Cause: the drill is set above or below the center axis.

5. The axis of the hole does not match the axis of the part at the end of the hole. Cause: in the material (sinks are possible in the way of drilling. The defect is irreparable.

6. The surface roughness of the hole does not correspond to the given one. Reason: high feed rate of the drill, the drill is blunt or incorrectly sharpened, wear of the ribbons, irregular removal of chips from the hole.

29. Drilling. The essence of the process, purpose and scope, equipment used (machine), tools, fixtures, dimensional accuracy and roughness of the surface being machined.

drilling- the main method of obtaining through and blind holes in the solid material of the workpiece. As tool used drill. Processing is done on drilling and turning machines. On the drilling machines the drill makes a rotational movement and a longitudinal movement along the axis of the hole, and the workpiece is fixed on the machine table. On lathes, the workpiece is fixed in a chuck and rotates, the drill is mounted in tailstock machine and performs a translational movement along the axis of the hole.

Fig.2. Schemes: a, b - drilling, c - reaming, d-sinking, d- deployment

The diameter of the hole to be drilled can be increased with a larger drill bit. Such operations are called reaming. When drilling, a relatively low accuracy and surface quality are provided.

To obtain holes of higher accuracy and less surface roughness, countersinking and reaming are performed. Countersinking machine pre-drilled holes with a multi-blade tool countersink, which has a more rigid working part. The number of teeth is at least three.

deployment you can correct inaccuracies in the shape of the hole. Reamers- a multi-blade tool that cuts very thin layers from the surface to be treated.

Purpose of drilling: Drilling is a necessary operation to obtain holes in various materials during their processing, the purpose of which is:

Making holes for threading, countersinking, reaming or boring.

Making holes (technological) for placing electric cables, anchor bolts, fasteners, etc.

Separation (cutting off) of workpieces from sheets of material.

Weakening of destructible structures.

The laying of an explosive charge in the extraction of natural stone.

Drilling operations are performed on the following machines:

Vertical drilling machines.

Horizontal drilling machines.

Vertical boring machines.

Horizontal boring machines.

Vertical milling machines.

Horizontal milling machines.

Universal milling machines.

Lathes (the drill is stationary and the workpiece is rotating).

Resurfacing lathes (drilling is an auxiliary operation, the drill is stationary).

To facilitate the cutting processes of materials, the following are used:

Cooling (water, emulsions, oleic acid, carbon dioxide, graphite).

Ultrasonic (ultrasonic vibrations of the drill increase productivity and chip breaking).

Heating (weakens the hardness of hard-to-cut materials).

Impact (during shock-rotary drilling (drilling) of stone, concrete).

30. Stretching. The essence of the process, purpose and scope, equipment used (machine), tools, fixtures, dimensional accuracy and roughness of the surface being machined.

Stretching- a high-performance method for processing parts of various shapes, providing high accuracy of shape and size processed surface. Due to the high cost tool - broaches, broaching is used in large-scale production. In broach, each cutting tooth is larger than the next by a certain amount. The cutting process during broaching is carried out on broaching vertical and horizontal executions of machine tools with the translational movement of the tool relative to a stationary workpiece in one pass.

Holes of various geometric shapes are drawn on horizontal broaching machines for internal broaching. Hole sizes from 5 to 250 mm.

Rice. 6. Schemes of broaching: 1 - workpiece, 2 - broach; a ... e - internal pulling; z ... w - external broaching

Cylindrical holes are pulled after drilling, boring or countersinking. Keyed and splined grooves are pulled by broaches, the shape of which in cross section corresponds to the profile of the hole being pulled.

External surfaces of various geometric shapes are broaching on vertical broaching machines for external broaching.

Broaching is used in large-scale and mass production of metal products, and rarely in small-scale and single. Broaches of various designs - external, internal, and mandrels, are among the most expensive instruments for metalworking. Sometimes each broach in its manufacture requires the highest precision and correct calculation. This is due to the fact that the tool during broaching works in the most difficult and harsh conditions of huge loads (tension, compression, bending, abrasive and adhesive chipping of broach blades). Broaching is preceded by preparatory metalworking operations, such as drilling, countersinking, reaming, punching (i.e., a fairly accurately machined surface of the workpiece is required to carry out broaching).

Dornovation(cornering) - a type of processing of workpieces without removing chips. The essence of mandrel is reduced to moving the workpiece in the hole with an interference fit of a rigid tool - a mandrel. Tool cross section dimensions more sizes cross-section of the hole of the workpiece by the amount of interference.

Broaching machines:

Horizontal broaching machines: All types of internal and external broaching of blanks.

Press: Processing holes with mandrel (piercing, shaping, calibration).

Stretch types:

Internal stretch. External stretch. Dornovation. glowing.